Walsworth U.S. Pat. application Ser. No. 410,497 filed Aug. 23, 1982 discloses a reciprocating fuel and oil pump in which the volume of oil pumped is variable relative to the fuel delivered. This permits the fuel to oil ratio to be varied to better suit the operating requirements of a two-stroke internal combustion engine. The oil pump piston of the fuel and oil pump has a variable stroke with the stroke being decreased by engagement with a stop positioned by means linked to the throttle linkage. The need for linkage between the throttle and the adjustable stop may impose design restraints.